The world is on fire

WASHINGTON — The Earth is burning up — literally.

The blaze that engulfed the Canadian town of Fort McMurray last week is just the latest of many gargantuan fires on a planet that has grown hotter with more extreme weather.

Earlier this year, large wildfires hit spots on opposite ends of the world — Tasmania in Australia and Oklahoma and Kansas in the United States. Last year, Alaska and California pushed the US to a record four million hectares burned. Massive fires hit Siberia, Mongolia and China last year, and Brazil’s fire season has increased by a month over the past three decades.

It got so bad that in 2009, Australia added a bright red “catastrophic” to its fire warning index.

“The warmer it is, the more fires we get,” said Mr Mike Flannigan, a professor of wildland fire at the University of Alberta, the province in Canada within which Fort McMurray is located.

Last week, temperatures pushed the mid-30°C mark in Alberta, which is unusual for May in northern Canada.

Many factors contribute to the complex reasons behind an increase in big fires, said Prof Flannigan and several experts. They include climate change, and the way people use land and firefighting methods that leave more fuel — trees and brush — to burn.

But the temperature one stands out, said Prof Flannigan.

“The Alberta wildfires are an excellent example of what we’re seeing more and more of: Warming means snow melts earlier, soils and vegetation dries out earlier, and the fire season starts earlier. It’s a train wreck,” wrote University of Arizona climate scientist Jonathan Overpeck in an email.

Worldwide, the length of Earth’s fire season increased nearly 19 per cent from 1979 to 2013, according to a study by Mr Mark Cochrane, a professor of fire ecology at South Dakota State University. Fires had steadily been increasing, but then, in the late 1990s and early 2000s, “we’ve suddenly been hit with lots of these large fires we can’t control”, he said.

In terms of hectares burned, the worldwide total may be dropping because of better firefighting, but in North America and Siberia “fires have grown quite a bit due to warming”, said Columbia University climate and ecology scientist Park Williams. “My estimate is that global warming has been responsible for about half of this increase.”

For the entire US, the 10-year average number of hectares burned in wildfires has more than doubled, from about 1.2 million hectares in the mid-1980s to 2.8 million hectares now, according to an analysis of government data by The Associated Press.

Twelve years before the Fort McMurray fire set northern Alberta ablaze, a study by Prof Flannigan and University of Victoria climate scientist Andrew Weaver found that “human-induced climate change has had a detectable influence” on a dramatic increase in wildfires in Canada.

Prof Flannigan said the area burned in Canada has doubled since the 1970s, “and we think that’s due to climate change”.

“Globally, we are seeing more fires, bigger fires, more severe fires,” said Dr Kevin Ryan, a retired US Forest Service scientist, now fire consultant.

Fires in some places, such as Indonesia and Canada, are bad when there is an El Nino — a warming of parts of the Pacific that changes weather worldwide — in play because it triggers drought in those regions, said Dr Ryan. In Indonesia, changes in land use are a bigger factor than climate, he added.

But elsewhere, it is temperature and moisture — too much of one and not enough of the other — that are the main factors, said scientists. As the air warms, it gets “more efficient at sucking the moisture out of the fuels”, which makes them more prone to burn, said Prof Flannigan. Add in lightning, and the ingredients are all there for a combustible mix.

A study found that lightning strikes increase 12 per cent with each 1°C rise in temperature, and that can trigger more fires. Prof Flannigan said there is evidence that fire-triggered clouds in Alberta caused at least two more fires because they created conditions for lightning.

The US National Academy of Sciences, in a study earlier this year, determined that “climate warming has resulted in longer fire seasons”. But other factors, such as the way fires are fought and land use, make it difficult to scientifically attribute individual fires and regional fires to climate change, said the report and other scientists.

But Canadian climate scientist Andrew Weaver, who is also a Green party legislator in the British Columbia Parliament, was adamant that the signs were all there.

“This is absolutely a harbinger of things to come,” he said. AP